A paragraph, according to Merriam-Webster is “a subdivision of a written composition that consists of one or more sentences, deals with one point or gives the words of one speaker, and begins on a new, usually indented line.”

That’s right — a paragraph can (and often does) contain just one sentence. Open any book, particularly any novel, to any random page, and I’ll bet you find somewhere nearby a single-sentence paragraph.

Single-sentence paragraphs are common in journalism, where tight, succinct prose and short, readable paragraphs are highly valued. They are abundant in narrative works that include dialogue (since a new paragraph is required every time a new speaker is quoted). But what about essays, research papers, and other typically academic types of writing? Shouldn’t paragraphs be fuller and more complex in those?

The answer is generally yes. Well-crafted essay paragraphs are normally fleshed out through several related sentences that illustrate a point or make a convincing argument. Please don’t hear me saying that it’s just fine to write one-sentence paragraphs whenever and wherever you like.

My point is simply that writing teachers ought to never suggest that there is some authoritative rule about the number of sentences required for a “proper” paragraph. It’s misleading and unnecessary. More than one WriteAtHome writing coach has come to us under the impression that it’s okay to demand some minimum number of sentences in every paragraph. If any of our coaches still believe that, well, I hope they read this post.

So how is it that so many students and teachers believe the three- or five-sentence paragraph rule? There’s a simple explanation, really. Students, like most human beings, are lazy. And if a teacher assigns a paragraph on a topic without specifying the length, some kid will submit a short, single sentence and expect full credit. In fact, once students learn that a complete sentence can be composed of a single word, and a paragraph can consist of a single sentence, it’s only a matter of time before some smarty-pants is assigned “a paragraph that shows action,” and submits this technically correct paragraph:

Go.

Only two letters, but grammatically, a complete sentence (the subject is the understood you).

So, to prevent this kind of silliness, teachers understandably began quantifying their expectations: Write a paragraph of at least five sentences that shows action. Some teachers probably made it a permanent policy: In this class, all paragraphs must have at least five sentences. All that is fine. It’s an artificially imposed rule for a particular academic purpose. No problem. The problems arose when teachers stopped making it clear that it was their rule rather than a universal rule of writing.

For the record, I think wise teachers and writing coaches should feel free to ask students to avoid one- or two-sentence paragraphs for any particular assignment or course. It can be a good instructional tool. But they must be sure to explain that the actual definition of paragraph permits the single-sentence variety. You have the power to raise expectations, but not to redefine the word.